The delivery of active pharmaceutical agents through the skin provides many advantages, including comfort, convenience, and non-invasiveness. This technology may also avoid gastrointestinal irritation and the variable rates of absorption and metabolism, including first pass effects, encountered in oral delivery. Transdermal delivery can also provide a high degree of control over blood concentrations of any particular active agent.
One method for transdermal delivery of such active agents involves the use of electrical current to actively transport the active agent into the body through intact skin by electrotransport. Electrotransport techniques may include iontophoresis, electroosmosis, and electroporation. Electrotransport devices, such as iontophoretic devices are known in the art. See, e.g., U.S. Pat. No. 6,216,033 B1 (Southam, et al.) One electrode, which may be referred to as the active or donor electrode, is the electrode from which the active agent is delivered into the body. The other electrode, which may be referred to as the counter or return electrode, serves to close the electrical circuit through the body. In conjunction with the patient's body tissue, e.g., skin, the circuit is completed by connection of the electrodes to a source of electrical energy, and usually to circuitry capable of controlling the current passing through the device. If the substance to be driven into the body is ionic and is positively charged, then the positive electrode (the anode) will be the active electrode and the negative electrode (the cathode) will serve as the counter electrode. If the ionic substance to be delivered is negatively charged, then the cathodic electrode will be the active electrode and the anodic electrode will be the counter electrode.
A switch operated therapeutic agent delivery device can provide single or multiple doses of a therapeutic agent to a patient by activating a switch. Upon activation, such a device delivers a therapeutic agent to a patient. A patient-controlled device offers the patient the ability to self-administer a therapeutic agent as the need arises. For example, the therapeutic agent can be an analgesic agent that a patient can administer whenever sufficient pain is felt.
There have been suggestions to provide different parts of an electrotransport system separately and connect them together for use. For example, it has been suggested that such connected-together systems might provide advantages for reusable controller circuit. In reusable systems, the drug-containing units are disconnected from the controller when the drug becomes depleted and a fresh drug-containing unit is then connected to the controller again. Examples of electrotransport devices having parts being connected together before use include those described in U.S. Pat. No. 5,320,597 (Sage, Jr. et al); U.S. Pat. No. 4,731,926 (Sibalis), U.S. Pat. No. 5,358,483 (Sibalis), U.S. Pat. No. 5,135,479 (Sibalis et al.), UK Patent Publication GB2239803 (Devane et al), U.S. Pat. No. 5,919,155 (Lattin et al.), U.S. Pat. No. 5,445,609 (Lattin et al.), U.S. Pat. No. 5,603,693 (Frenkel et al.), WO1996036394 (Lattin et al.), and US 2008/0234628 A1 (Dent et al.).
There remain issues to be resolved and problems to be overcome in the art of electrotransport of therapeutic agents.